Mark Watney is admittedly the least important member of his NASA team. He’s not the commander, and his role as botanist isn’t the most integral to surviving on a mission to Mars. So when a sandstorm collides with his crew, he’s left behind, assumed dead by his crew mates, and wakes up millions of miles away from any other human being, he’s a little freaked out. But Mark Watney has underestimated himself. He quickly gets to work, figuring out how much food, water and oxygen he has left in his spaceship. It’s not enough to sustain more than a few months. Finally his botany background helps out, as he finds ways to grow food and create more oxygen and water to lengthen his lifespan.

It takes a while before NASA recognizes that he’s still alive. He was assumed dead by his crew mates, NASA and in turn, the entire world. It becomes as much NASA’s all-consuming goal to save him as Mark has to stay alive. He overcomes obstacle after obstacle over the course of more than a year until he can, maybe, be saved.

The book tells the story through Mark’s first-person journal entries narration of what’s going on on Earth and on the other spaceship where Mark’s crew mates remain. The movie is brilliant in its decision to turn Mark’s journal entries into video logs. It’s more visual and actually makes more sense; considering Mark is alone on Mars, he should want a reason to talk and pretend someone is listening. I was also impressed the movie kept the book’s humor. Despite the bleakness of Mark’s challenge, he always impressively kept up his spirits — making fun of the disco music his commander left behind, calling himself the “best botanist on the planet,” and praising the wonder and beauty of duct tape. It was great to see all of that in the movie. Plus, Matt Damon has great comedic delivery.

That said, the movie left some things out, likely for time. Probably Mark’s largest obstacle is a massive sandstorm that makes it hard for him to travel to the area on Mars where he’s supposed to make contact with his crew mates. It’s a supremely harrowing section of the book, and I was shocked that it was cut from the movie. Granted, he still had plenty of other troubles to deal with, but to have taken out the biggest one was surprising. The movie also altered the ending a bit; it changed which crew member grabs Mark in space and makes Mark a little more heroic in that moment.

Probably the biggest change is the very end of the movie, the epilogue-like scene of Mark after the NASA debacle. It includes an overstated speech that differs from the points Mark makes at the end of the novel. It shouldn’t have differed so much because the last few pages of the novel are some of the book’s best and are a great, grand statement on human nature. But ultimately, this is one of the few movies out there that follows the book so closely, and besides those few, mostly minor changes, both the movie and book are great.